In recent years, projectors using solid-state light sources such as light emitting diodes (LEDs) or laser diodes (LDs) as light sources have become widespread. Some light sources for the projectors use the solid-state light sources such as LDs as direct light sources while others use light from the solid-state light sources as excitation light and use fluorescent substances emitting fluorescent light due to irradiation with the excitation light as light sources.
Thus, various technologies for efficiently irradiating the fluorescent substances with the light from solid-state light sources have been developed. For example, Patent Literature 1 discloses a light source device that reflects light from a solid-state light source by a concave mirror and collects the light on a fluorescent substance.